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<a name="Function-Types"></a>
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<a name="Function-Types-1"></a>
<h3 class="section">5.11 Function Types</h3>

<p>Various types can be defined for function variables.  These types are
not used in defining functions (see <a href="Procedures.html#Procedures">Procedures</a>); they are used for
things like pointers to functions.
</p>
<p>The simple, traditional, type is type descriptor &lsquo;<samp>f</samp>&rsquo; is followed by
type information for the return type of the function, followed by a
semicolon.
</p>
<p>This does not deal with functions for which the number and types of the
parameters are part of the type, as in Modula-2 or ANSI C.  AIX provides
extensions to specify these, using the &lsquo;<samp>f</samp>&rsquo;, &lsquo;<samp>F</samp>&rsquo;, &lsquo;<samp>p</samp>&rsquo;, and
&lsquo;<samp>R</samp>&rsquo; type descriptors.
</p>
<p>First comes the type descriptor.  If it is &lsquo;<samp>f</samp>&rsquo; or &lsquo;<samp>F</samp>&rsquo;, this
type involves a function rather than a procedure, and the type
information for the return type of the function follows, followed by a
comma.  Then comes the number of parameters to the function and a
semicolon.  Then, for each parameter, there is the name of the parameter
followed by a colon (this is only present for type descriptors &lsquo;<samp>R</samp>&rsquo;
and &lsquo;<samp>F</samp>&rsquo; which represent Pascal function or procedure parameters),
type information for the parameter, a comma, 0 if passed by reference or
1 if passed by value, and a semicolon.  The type definition ends with a
semicolon.
</p>
<p>For example, this variable definition:
</p>
<div class="example">
<pre class="example">int (*g_pf)();
</pre></div>

<p>generates the following code:
</p>
<div class="example">
<pre class="example">.stabs &quot;g_pf:G24=*25=f1&quot;,32,0,0,0
    .common _g_pf,4,&quot;bss&quot;
</pre></div>

<p>The variable defines a new type, 24, which is a pointer to another new
type, 25, which is a function returning <code>int</code>.
</p>



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